Automatic transmissions of the type employed in family automobiles, light trucks, and even heavy trucks, such as tractors for highway trailers, commonly employ a mechanical gear train with a hydraulic connector on the input side of said transmission. The hydraulic connector usually comprises a mechanism not unlike a pair of fans facing each other wherein one fan is driven and the other rotates from the current of air from the driven fan. Thus, a coupling of this kind comprises two rotating parts fitted with radially extending vanes, one of which is the driving member or impeller, and the other of which is the driven member or turbine. As assembled, the impeller and turbine define a torus wherein hydraulic oil flung by the engine-connected impeller drives the turbine and its associated mechanical gear train.
When repair or overhaul is indicated for an automatic transmission of this type, it is often found that the drive shaft or hub of the impeller is worn to the extent that it must be replaced. Since the drive shaft is integral with the impeller, it has heretofore been necessary to either replace the impeller assembly with a new one, or remove the tubular hollow drive shaft of the freed impeller and replace it in the impeller assembly.
Neither case provides an economical repair. In one case, the welded bond between the drive shaft and the impeller must be cut away and a new drive shaft welded into the assembly after painstakingly aligning the drive shaft and impeller to preserve concentricity. As a practical matter, it is almost always true that concentricity must be corrected after a new drive shaft hub is installed. In the other case, replacement of the entire impeller assembly is relatively expensive.
It was previously known that a method and apparatus for repairing worn torque converter impeller drive shafts employed the steps of separating the impeller from the transmission assembly, separating the drive shaft from the impeller, installing by welding a new drive shaft with the old impeller, and then realigning the assembly of the new drive shaft with the old impeller.
In the U.S. Pat. to J. A. Ferris, Sr., No. 3,541,665, issued on Nov. 24, 1970, there is disclosed a method and apparatus for resizing the collapsed core which is usually of very heavy laminated paper construction of a roll or coil of material. The method and apparatus disclosed in the patent to Ferris provides a power-driven, bullet-shaped die which is thrust into the deformed core aperture to radially expand the core to its original circular cross-section.
The U.S. Pat. to Powell et al., No. 3,557,435, issued on Jan. 26, 1971, discloses a Method For Repairing Bungholes, in which a weld ring aroung the bunghole is removed, the void is cleaned out, and the groove filled with new weld metal. Another patent of interest is the U.S. Pat. to Grant, No. 3,237,292, granted on Mar. 1, 1966, for Method And Means For Resizing Pistons And Like Hollow Articles.
Techniques which were well known in forging and blacksmithing used a hole in a metal workpiece. The workpiece was heated to a malleable state and enlarged by forcing successively larger diameter dies through the workpiece. Thus, a malleable tubular workpiece may be radially expanded by forcing a bullet-shaped die therethrough, and a thick-wall workpiece of the same type may be heated to a malleable state before forcing the die through the workpiece. The well-known collet chuck has flexible fingers arranged to be cammed inward to grip a cylindrical workpiece.